EV Charging Time Calculator
Estimate how long a Level 2 charger may take to add energy to an electric vehicle battery.
Charging details
Efficiency and power factor vary by vehicle, charger, current, and operating conditions. Replace the defaults with measured or manufacturer data when available.
Estimated charging time
The estimate assumes steady charging power across the selected charge range.
About this calculator
Enter the vehicle’s usable battery capacity, current and target charge levels, and the EVSE’s output voltage and current. The calculator estimates the energy added to the battery and divides it by estimated battery charging power.
This is a charging-time estimate. It does not size the branch circuit, verify an EVSE installation, or calculate an electrical service load.
Method and assumptions
Energy to add = usable battery capacity × (target charge − starting charge). Apparent AC power = charging voltage × charging current. Estimated battery charging power = apparent power × power factor × efficiency. Estimated time = energy to add ÷ battery charging power. The displayed time rounds to the nearest minute and shows “Under 1 min” for shorter estimates.
The calculation assumes steady charging power throughout the selected charge range. It does not model vehicle charge curves, battery temperature, auxiliary loads, or EVSE power sharing.
Interpret the result
Use the result as an approximate planning range. Actual charging time depends on the vehicle’s onboard charger, the EVSE and circuit limits, battery temperature, charge-level taper, and other vehicle loads.
FAQs
What battery capacity should I enter?
Enter the vehicle’s usable battery capacity, not its gross pack capacity. Check the vehicle display or manufacturer specifications for the usable value.
Why can actual charging take longer?
This estimate assumes constant charging power. A vehicle may reduce charging power as the battery approaches its target charge or when battery temperature, vehicle settings, or the electrical supply limit charging.
Does this check the branch circuit or service?
No. This tool estimates charging time only. Use the EVSE Circuit and Service Load Planner for separate screening checks, then verify the equipment instructions and locally adopted electrical requirements.
Why are power factor and efficiency inputs included?
AC voltage and current give apparent power. Power factor estimates real AC input power, and charging efficiency estimates how much of that input reaches the battery. Use vehicle-specific data when available.
Sources
- U.S. Department of Energy Alternative Fuels Data Center, Developing Infrastructure to Charge Electric Vehicles — Level 2 charging uses 208 V or 240 V AC equipment.
- NREL, Electric Vehicle Charging Impacts and Opportunities for Utilities — includes a modeling example using 90% onboard charger efficiency; actual efficiency varies by vehicle and operating conditions.